1. Field of the Invention
The present invention relates to a missile or aircraft with a hierarchical closed-loop flow control system and more particularly to aircraft or missile with a flow control system for aerodynamic control, maneuverability and stabilization. The present invention further relates to a method of operating the flow control system.
2. Technical Background
Traditional aircraft and missile maneuvering technologies utilize hinged control surfaces such as the wings, tail-fins and forebody-canards to provide control and stability through all phases of an aircraft's or missile's flight path. These control surfaces require significant volume to house the control actuation system, which includes heavy servomotors, thereby imposing significant limitations on the aircraft or missile's aerodynamic performance. These hinged-control surfaces also reduce the effective payload, maximum achievable range, and lethality of missiles and aircraft.
Conventional missile and aircraft control techniques are not capable of meeting new multi-mission highly accurate, long-range fire requirements that are needed to ensure the multi-target engagement capabilities of missiles or aircraft, particularly “smart” missiles and aircraft. In addition, with a missile the overall cost of the control system per round needs to be minimum without affecting the aerodynamic efficiency of the missiles considering their subsistence period once deployed. The major disadvantages of traditional control surfaces is space restriction, i.e., control surfaces must be located in an annular space around the throat of the propulsion nozzle; increased weight; and drag from exposed surfaces. The conventional control surfaces necessitate hinges, which increase the overall weight induced aerodynamic drag and also the complexity of the propulsion system. There is therefore a need for a distributed control system for improving performance of aircraft, missiles and munitions.
Active flow control enables a mechanism to alter the flow around the aerodynamic surface(s) in order to achieve a desired air vehicle maneuver by utilizing micro-actuators that are located optimally on the aerodynamic surface of air vehicles. Most of the active flow control systems currently in use, or under investigation, operate in the open-loop mode, i.e., the control input (via micro-actuators) is not continuously adjusted based on the sensor information. Such open-loop flow control systems fail to maintain the required aerodynamic performance of the air vehicle under dynamic conditions. Dynamic, in this context, is referred to flow instabilities or vehicle motion. In view of the foregoing disadvantages of currently used control surfaces and open-loop flow control systems, it has become desirable to develop a robust, closed-loop, active flow control system that provides the necessary control moments in real-time by utilizing fast-response sensors and fast-acting control actuators, so as to maintain and enhance the overall aerodynamic performance of the missile or the aircraft. It is further desirable to develop a flow control system for missile and aircraft control that enables low-cost, low-weight and low-volume sensor-actuator-controller modules to control local flow phenomena for enhanced aerodynamic performance. It is still even further desirable to develop a missile, aircraft and munition control system that can control numerous flow control devices with associated sensors using a multi-tiered, hierarchical control architecture using a higher level controller for real-time aerodynamic control.